This invention relates generally to transmission testers and methods of testing transmissions, especially rebuilt automatic transmissions for automobiles and trucks. More specifically, the invention is directed to transmission test apparatus to which an automatic transmission may be mounted, in driven relation to, in combination, a prime mover and a braking apparatus, for simulating driving conditions in a vehicle, and to novel braking apparatus.
Automatic transmission test stands are generally known. Typical of such test stands is the test stand taught in, for example, U.S. Pat. No. 4,732,036 Weeder. Weeder teaches a test stand wherein the headstock, which receives the transmission thereon while the transmission is being tested, can move transverse to the tailstock shafts, as well as being able to move vertically. The prime mover internal combustion engine also can move transversely as well as vertically, but on supports separate from the headstock supports.
U.S. Pat. No. 4,356,724 Ayoub et al teaches using an electric motor as the prime mover, as does U.S. Pat. No. 5,142,903 Mizushina et al. Ayoub et al show the electric motor fixedly secured to a support remote from the headstock support. Mizushina et al do not show the mounting support for the electric motor. Neither reference teaches any electronic apparatus for conditioning the electricity supplied to the electric motor.
In all the references known to the inventor, only flywheel-type inertia devices are taught as load devices, for applying a load to the engine during the test procedure.
No reference known to the inventor provides a single test stand for testing automatic transmissions wherein the headstock is mounted to the main frame with sufficient freedom of movement to mount and test all of (1) rear wheel drive transmissions, (2) transverse mounted front wheel drive transmissions, and (3) longitudinally mounted front wheel drive transmissions.
No reference teaches or suggests mounting an electric motor as the prime mover to the same support that mounts the headstock which receives the transmission. Neither does any reference teach using electric brakes.
It is an object of this invention to provide an improved transmission tester, and methods of use, wherein an electric motor is provided as the prime mover, fixedly secured for adjusting movement relative to a braking unit, in combination with the headstock and corresponding transmission secured to the headstock.
It is another object to provide a transmission tester, and methods of use, wherein an electric motor is provided as the prime mover, and is adapted to temporarily suspend acceleration when the transmission shifts gears.
It is a further object to provide a transmission tester wherein the headstock can pivot about a vertical axis, to thereby receive a longitudinally mounted transaxle, as well as to receive transversely mounted transaxles and rear wheel drive transmissions.
It is another object to provide a load device, for providing an active load simulating the deadweight load of a range of vehicle weights.
It is a more specific object to provide a load device adapted to apply a mechanical resistance load within a range of available torque values, including selecting one or more torque values as part of testing each transmission.
It is a still more specific object to provide an eddy current brake as an active load device, for applying resistance torque to the transmission while the transmission is being tested.
The invention generally comprehends improvements in transmission testing apparatus, including use of eddy current brakes, pivoting the headstock about a substantially vertical axis, and providing enhanced electrical controls that allow use of an electric motor prime mover while simulating the loading characteristics of an internal combustion engine.
Some of the objects are obtained in a first family of embodiments comprehending a transmission tester for testing vehicular transmissions, the transmission tester comprising a main frame; a prime mover, for providing driving energy to a transmission to be tested; a headstock plate adapted to receive thereon a transmission to be tested, the headstock plate being supported from the main frame by a support, for pivoting the headstock plate about a first axis; and braking apparatus, supported from the main frame, the braking apparatus including a shaft journalled for rotation about a second axis substantially perpendicular to the first axis, and extending generally toward the headstock plate, for engaging an output shaft of the transmission to be tested, and for thereby applying braking energy to the transmission.
In preferred embodiments, the first axis is substantially vertical and the second axis is substantially horizontal. The support comprises a headstock frame, supported from the main frame, between the main frame and the headstock plate, the headstock frame being mounted for pivotation about the first axis, thereby to pivot the headstock plate about the first axis, with the headstock plate being adapted to face in a first direction along an imaginary line extending toward the brake unit, and to pivot about the first axis to thereby face in a second direction transverse to the imaginary line extending toward the brake unit. Accordingly, the headstock plate can pivot about an included angle, between the first and second directions, of at least about 90 degrees.
The transmission tester preferably has opposing first and second ends, and a length therebetween, the prime mover comprising an electric motor, mounted to the headstock frame, the headstock frame, with the electric motor thereon, being supported from the main frame for movement both of the combination of the headstock frame and the electric motor in a direction having a vertical component, and of the combination of the headstock frame and the electric motor in a direction having a transverse horizontal component relative to the length of the transmission tester.
In preferred embodiments, the prime mover comprises an electric motor, mounted for pivotation with respect to the first axis, and includes an inverter adapted to vary the speed of the electric motor, and to temporarily suspend acceleration of the speed of the electric motor when a transmission being tested shifts gears.
In highly preferred embodiments, the prime mover comprises an electric motor mounted to the headstock frame, and the headstock plate is mounted to the headstock frame, for pivoting both the prime mover and the headstock plate, in combination, with respect to the first axis.
The braking apparatus preferably comprises an eddy current brake.
In a second family of embodiments, the invention comprehends a transmission tester for testing vehicular transmissions, the transmission tester comprising a main frame; a prime mover, for providing driving energy to a transmission to be tested; a headstock plate, supported from the main frame, for receiving thereon transmissions to be tested; and braking apparatus, supported from the main frame, the braking apparatus comprising a connecting shaft journalled for rotation about a first axis, and for applying braking energy to a transmission to be tested, the braking apparatus being adapted to dynamically apply a resistance torque which varies within a range of vehicle deadweight loads, and braking loads, simulating a correspondingly varying range of vehicle deadweight loads, and braking loads, preferably comprising an eddy current brake.
In preferred transmission testers of the invention, the eddy current brake has a longitudinal axis defining a length, a shaft extending along the longitudinal length of the brake, a stator, including at least first, second, third, and fourth electromagnetic stator coils disposed in side-by-side relationship with each other about the shaft, and an end pole associated with each electromagnetic stator coil, and a rotor secured to the shaft, for rotation with the shaft and adjacent the end pole, with a gap between the rotor and the end poles, the electromagnetic stator coils being wired in series, from the first coil to the fourth coil, preferably in the sequence of first, second, third, and fourth coils.
In some embodiments, the at least first, second, third, and fourth electromagnetic stator coils comprise a first front set of coils, the eddy current brake further comprising a corresponding second rear set of electromagnetic stator coils disposed rearwardly of the first front set, and in side-by-side relationship with each other about the shaft, the second set of coils being wired in parallel with the first set of coils, and, at least in part, in series with each other.
Preferably, the braking apparatus further comprises a direct current motor control adapted to receive alternating current up to 230 volts, to transform the alternating current to a lower voltage of 96 volts alternating current, to convert the lower voltage alternating current to 96 volts direct current, and to supply the 96 volts direct current to the electromagnetic stator coils. The braking apparatus may further include a potentiometer adapted to regulate and control amperage delivered from the direct current motor control to the electromagnetic stator coils, thereby to control, and optionally vary dynamically, during testing of a given transmission, amperage, and thus the load applied to the transmission by the braking apparatus.
Further to preferred embodiments, the eddy current brake may comprise at least three electromagnetic stator coils effective to apply braking energy to a transmission to be tested, the eddy current brake and an electrical control unit, in combination, being adapted to apply electrical energy to at least three, more preferably all, of the at least three electromagnetic stator coils at the beginning of applying energy to the eddy current brake to thereby apply braking torque to a transmission to be tested.
The prime mover preferably comprises an electric motor, and includes an inverter adapted to vary the speed of the electric motor, and to temporarily suspend acceleration of the speed of the electric motor when a transmission being tested shifts gears.
It is also preferred that the transmission tester of the invention include a mechanical stall brake, for mechanically locking the connecting shaft of the eddy current brake against rotation about the first axis.
In a third family of embodiments, the invention comprehends a method of testing a vehicular transmission. The method comprises the steps of providing a transmission tester having a main frame, a prime mover, for providing driving energy to a transmission to be tested, a headstock plate adapted to receive thereon a transmission to be tested, the headstock plate being supported from the main frame, for pivoting the headstock plate about a first axis, and braking apparatus, supported from the main frame, the braking apparatus including a shaft journalled for rotation about a second axis substantially perpendicular to the first axis, and extending generally toward the headstock plate, for engaging an output shaft of the transmission to be tested, and for thereby applying braking energy to the transmission; mounting, to the headstock plate, a transmission to be tested; and as necessary, pivoting the headstock plate about the first axis to bring the output shaft on the transmission into alignment with the shaft on the braking apparatus.
Preferably, the support comprises a headstock frame, supported from the main frame, between the main frame and the headstock plate, the headstock frame being mounted for pivoting about the first axis, the method thereby comprising pivoting the headstock frame to effect the pivoting of the headstock plate about the first axis.
Also preferably, the method comprises facing the headstock plate in a first direction along an imaginary line extending toward the brake unit, and pivoting the headstock plate about the first axis to thereby face in a second direction transverse to the line extending toward the brake unit, thereby describing an included angle between the first and second directions of at least about 90 degrees.
In some preferred embodiments, the support comprises a headstock frame, supported from the main frame, between the main frame and the headstock plate, the headstock frame being mounted for pivotation about the first axis, the transmission tester having first and second ends, and a length therebetween, the prime mover comprising an electric motor, mounted to the headstock frame, the headstock frame, with the electric motor thereon, being supported from the main frame for both movement of the combination of the headstock frame and the electric motor in a direction having a vertical component and movement of the combination of the headstock frame and the electric motor in a direction having a transverse horizontal component relative to the length of the transmission tester, the method further comprising pivoting the combination of the headstock frame and the electric motor about the first axis, and moving the combination of the headstock frame and the electric motor in one or more directions comprising movement having both vertical and horizontal components.
In other embodiments, the prime mover comprises an electric motor, the method further comprising supplying electric power to the electric motor and thereby driving a transmission being tested at an accelerating speed, including conditioning the electric power in an inverter and thereby increasing the speed of the electric motor, and, through the inverter, temporarily suspending acceleration of the speed of the electric motor when the transmission shifts gears.
It is preferred that the braking apparatus comprise an eddy current brake, adapted to dynamically apply a resistance torque to the transmission, wherein the load varies within a range of available torque values, simulating a correspondingly varying range of vehicle deadweight loads, and braking loads, the method comprising selecting at least one torque deadweight value, and optionally a dynamically variable set of braking loads as part of testing each transmission, and applying the selected loads to the transmission, as resistance torque, using eddy current power.
As to pivotation about the first axis, it is preferred that the prime mover comprise an electric motor, mounted to the headstock frame, and the headstock plate being mounted to the headstock frame, and that the method include pivoting both the prime mover and the headstock plate, in combination, with respect to the first axis.
In some applications of the invention, the transmission tester includes a stall brake, and the method includes applying driving power from the prime mover to the transmission mounted to the headstock plate, and simultaneously applying the stall brake, for performing e.g. a stall speed test on the transmission.
In a fourth family of embodiments, the invention comprehends a method of testing vehicular transmissions, the method comprising the steps of providing a transmission tester having a main frame, a prime mover, for providing driving energy to a transmission to be tested, a headstock plate adapted to receive thereon a transmission to be tested, the headstock plate being supported from the main frame, and braking apparatus, supported from the main frame, the braking apparatus including a connecting shaft journalled for rotation about a first axis, and for applying braking energy to a transmission, the braking apparatus comprising an eddy current brake; mounting, to the headstock plate, a transmission to be tested; connecting an output element, such as a shaft, of the transmission to the connecting shaft of the braking apparatus; applying energy from the prime mover to thereby drive the transmission; and applying electrical energy to the braking apparatus and thereby applying eddy current power, as a braking torque, to the transmission output element.
Preferably, the method includes receiving, in an electrical control unit, alternating current up to 230 volts, transforming the alternating current to 96 volts, converting the 96 volt alternating current to 96 volts direct current, and applying the 96 volt direct current to the eddy current brake to thereby apply eddy current power to the transmission, optionally including controlling amperage to the transformer, and thus to the eddy current brake, and thereby applying a varying amount of braking torque to the transmission.
In preferred embodiments, the eddy current brake comprises at least three electromagnetic stator coils effective to apply braking energy to the transmission, the eddy current brake and the electrical control unit, in combination, being adapted to apply electrical energy to at least three of the at least three electromagnetic stator coils at the beginning of applying energy to the eddy current brake to thereby apply braking torque to the transmission, the method including applying electrical energy, through the electrical control unit, to at least three of the at least three, preferably all, electromagnetic stator coils at the beginning of applying energy to the eddy current brake to thereby apply braking torque to the transmission.
In preferred methods, the eddy current brake has a longitudinal axis defining a length, and comprises a shaft extending along the longitudinal length of the brake, a stator, including at least first, second, third, and fourth electromagnetic stator coils disposed in side-by-side relationship with each other about the shaft, and an end pole associated with each electromagnetic stator coil, and a rotor secured to the shaft, for rotation with the shaft and adjacent end poles, with a gap between the rotor and the end poles, the method including applying electrical energy to the at least first, second, third, and fourth electromagnetic stator coils in series relationship, from the first coil to the fourth coil.
In some embodiments, the at least first, second, third, and fourth electromagnetic stator coils comprise a first front set of coils, the eddy current brake comprising a corresponding second rear set of electromagnetic stator coils disposed rearwardly of the first front set, in side-by-side relationship with each other about the shaft, the method including applying electrical energy to the second set of electromagnetic stator coils in parallel with the first set of electromagnetic stator coils, and, at least in part, in series with each other.
The braking apparatus may further comprise a direct current motor control adapted to receive alternating current up to 230 volts, to transform the alternating current to 96 volts, to convert the 96 volts alternating current to 96 volts direct current, and to supply the 96 volts direct current to the electromagnetic stator coils.
The method may further comprise regulating and controlling amperage delivered from the direct current motor control to the electromagnetic stator coils with a potentiometer.
In preferred embodiments, the prime mover comprises an electric motor, the method further comprising supplying electric power to the electric motor and thereby driving the transmission at an accelerating speed, including conditioning the electric power in an inverter and thereby increasing the speed of the electric motor, and, through the inverter, temporarily suspending acceleration of the speed of the electric motor, and thereby the speed of the transmission, when the transmission shifts gears.
In some embodiments, the transmission tester includes a mechanical stall brake, and the method includes applying the stall brake, and thereby mechanically locking the eddy current brake against rotation about the first axis.